1. Institute of Molecular Science; 030006 Taiyuan P. R. China
2. Institute of Applied Chemistry; Shanxi University; 030006 Taiyuan P. R. China
3. Department of Chemistry; Changzhi University; 46011 Changzhi P. R. China
4. School of Chemistry and Chemical Engineering; Shanxi University; 030006 Taiyuan P. R. China